/Engine/Source/Runtime/Engine/Classes/Materials/MaterialFunctionInstance.h
virtual bool GetParameterOverrideValue ( EMaterialParameterType Type, const [FName](API\Runtime\Core\UObject\FName) & ParameterName, [FMaterialParameterMetadata](API\Runtime\Engine\FMaterialParameterMetadata) & OutValue, FMFRecursionGuard RecursionGuard ) const